MaxCoderz

Code: Select all

div_h_l:	;returns e = h/l
		;c if error, nc if OK
		;kills af, e, hl
		;A/B (just names, will be used in comments)
	ld a,l
	or a
	ccf
	ret z	;return C if dividing by 0
	ld a,h
	cp l
	jr nc,{+}
	;divisor > dividend, return 0 but no error
	xor a
	ld e,a
	ret
+:	;all normal, divide
	ld h,1	;index, that's a one, a bit hard to see in this font
	;there is only 1 one in this code, namely this one.
	;MSbit line-up
-:	cp l  ;that's an L
	jr c,_shiftdone_goback
	bit 7,l
	jr nz,_shiftdone
	;shift
	add hl,hl	;L+L can never carry
	jr {-}
_shiftdone_goback:
	srl l
	srl h
_shiftdone:
	sub l
	ld e,h		;result = 0 + index
	ld d,a
-:	ld a,h
	or a
	ret z
	rra	;index >> 1
	ld h,a
	srl l	;B >> 1
	;if A>=B
	ld a,d
	cp l
	jr c,{-} ;A<B
	sub l
	ld d,a
	ld a,e
	add a,h
	ld e,a
	jr {-}

Code: Select all

div_hl_de:	;returns hl = hl / de
		;c if error
	ld a,d
	or e
	ccf
	ret z
	
	ld a,d
	cp h
	jr c,{+}
	ld a,e
	cp l
	jr c,{+}
	ld hl,0
	ret
+:	;MSbit line-up
	ld bc,1
	
-:	ld a,h
	cp d
	jr c,_goback
	ld a,l
	cp e
	jr c,_goback
	bit 7,h
	jr nz,_continue
	sla c
	rl b
	sla e
	rl d
	jr {-}
_goback:
	srl d
	rr e
	srl b
	rr c
_continue:
	or a
	sbc hl,de
	;hl = A
	;de = B
	;bc = index
	
	push hl
	ld h,b
	ld l,c		;hl = result, stacktop = A
	
-:	ld a,b
	or c
	jr nz,{+}
	pop de
	ret
+:	srl d
	rr e
	srl b
	rr c
	ex (sp),hl  ;I don't see this one a lot - maybe it's proof of how braindead I am..
	;hl = A, stacktop = result
	or a
	sbc hl,de
	jr c,_wassmaller
	ex (sp),hl
	add hl,bc
	jr {-}
_wassmaller:
	adc hl,de
	ex (sp),hl
	jr {-}